<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8" />
  <meta http-equiv="X-UA-Compatible" content="IE=edge" />
  <meta name="viewport" content="width=device-width, initial-scale=1.0" />
  <link rel="stylesheet" href="./styles/index.css" />
  <title>Document</title>
</head>

<body>
  <div id="app" class="score-case">
    <div class="table">
      <table>
        <thead>
          <tr>
            <th>编号</th>
            <th>科目</th>
            <th>成绩</th>
            <th>操作</th>
          </tr>
        </thead>
        <tbody v-if="list.length>0">
          <tr v-for="(item,index) in list" :key="item.id">
            <td>{{index+1}}</td>
            <td>{{item.subject}}</td>
            <td :class="{red :item.score<60}">{{item.score}}</td>
            <td><a href="#" @click.prevent="remove(item.id)">删除</a></td>
          </tr>

        </tbody>
        <tbody v-else>
          <tr>
            <td colspan="5">
              <span class="none">暂无数据</span>
            </td>
          </tr>
        </tbody>

        <tfoot>
          <tr>
            <td colspan="5">
              <span>总分：{{getTotal}}</span>
              <span style="margin-left: 50px">平均分：{{getAvg}}</span>
            </td>
          </tr>
        </tfoot>
      </table>
    </div>
    <div class="form">
      <div class="form-item">
        <div class="label">科目：</div>
        <div class="input">
          <input type="text" placeholder="请输入科目" v-model.trim="subject" />
        </div>
      </div>
      <div class="form-item">
        <div class="label">分数：</div>
        <div class="input">
          <input type="number" placeholder="请输入分数" v-model.number="score" />
        </div>
      </div>
      <div class="form-item">
        <div class="label"></div>
        <div class="input">
          <button class="submit" @click="add()">添加</button>
        </div>
      </div>
    </div>
  </div>
  <script src="https://cdn.jsdelivr.net/npm/vue@2/dist/vue.js"></script>

  <script>
    const app = new Vue({
      el: '#app',
      data: {
        list: [
          { id: 1, subject: '语文', score: 20 },
          { id: 7, subject: '数学', score: 99 },
          { id: 12, subject: '英语', score: 70 },
        ],
        subject: '',
        score: ''
      },
      methods: {
        remove(id) {
          this.list = this.list.filter(item => item.id !== id)
        },
        // 添加
        add() {
          if (this.subject == '' || this.score == '') {
            return alert('请输入学科名称和分数')
          }
          if (this.subject.length < 2) {
            return alert('学科名称不能少于两个字')
          }
          if (this.score < 0 || this.score > 100) {
            return alert('分数必须在0-100之间')
          }
          this.list.unshift({
            id: Date.now(),
            subject: this.subject,
            score: +this.score
          }),
            this.subject = '',
            this.score = ''
        },

      },
      computed: {
        // 总分
        getTotal() {
          const res = this.list.reduce((total, item) => total + item.score, 0)
          return res
        },
        // 平均分
        getAvg() {
          if (this.list.length == 0) {
            return 0
          }
          return (this.getTotal / this.list.length).toFixed(1)
        }
      }
    })
  </script>
</body>

</html>